Trichinella spiralis is an intracellular nematode parasite of mammalian skeletal muscle cells. This zoonotic parasite is found throughout the world and remains a public health concern in countries which lack effective intervention strategies. Chronically infected muscle cells have greatly reduced levels of myofibrillar proteins secondary to transcriptional repression. How and when this transcriptional repression is induced has yet to be determined. It has been shown that chronically infected muscle cells have a DNA content compatible with G2/M phase cells. Since, muscle gene expression appears to be exclusive to G0, the observed muscle gene repression may be a consequence of parasite induced repositioning within the cell cycle. In the proposed studies, 1) the cell cycle phase of chronically muscle cells and the activity of cdc2 histone kinase, if present, will be assessed and 2) in situ hybridization will be utilized to determine transcriptional activity of select genes during infection. This strategy is designed to clarify the importance of cell cycle repositioning to the development of the infected cell phenotype. Once completed, these studies will provide direction for the identification of pivotal parasite products and for the development of novel intervention strategies.